Nonunion After Clavicle Osteosynthesis: High Incidence of Propionibacterium acnes

Surprise positive culture rate in the treatment of presumed aseptic long-bone nonunion: a systematic review with meta-analysis of 2397 patients

INTRODUCTION

In pre-operatively presumed aseptic nonunions, the definitive diagnosis of infection relies on intraoperative cultures. Our primary objective was to determine (1) the rate of surprise positive intraoperative cultures in presumed aseptic long-bone nonunion (surprise positive culture nonunion), and (2) the rate of surprise positive cultures that represent infection vs. contamination. Secondary objectives were to determine the healing and secondary surgery rates and to identify cultured micro-organisms.

MATERIALS AND METHODS

We performed a systematic literature search of PubMed, Embase and Cochrane Libraries from 1980 until December 2021. We included studies reporting on ≥ 10 adult patients with a presumed aseptic long-bone nonunion, treated with a single-stage surgical protocol, of which intraoperative cultures were reported. We performed a meta-analysis for: (1) the rates of surprise positive culture nonunion, surprise infected nonunion, and contaminated culture nonunion, and (2) healing and (3) secondary surgery rates for each culture result. Risk of bias was assessed using the QUADAS-2 tool.

RESULTS

21 studies with 2,397 patients with a presumed aseptic nonunion were included. The rate of surprise positive culture nonunion was 16% (95%CI: 10-22%), of surprise infected nonunion 10% (95%CI: 5-16%), and of contaminated culture nonunion 3% (95%CI: 1-5%). The secondary surgery rate for surprise positive culture nonunion was 22% (95%CI: 9-38%), for surprise infected nonunion 14% (95%CI 6-22%), for contaminated culture nonunion 4% (95%CI: 0-19%), and for negative culture nonunion 6% (95CI: 1-13%). The final healing rate was 98% to 100% for all culture results. Coagulase-negative staphylococci accounted for 59% of cultured micro-organisms.

CONCLUSION

These results suggest that surprise positive cultures play a role in the clinical course of a nonunion and that culturing is important in determining the etiology of nonunion, even if the pre-operative suspicion for infection is low. High healing rates can be achieved in presumed aseptic nonunions, regardless of the definitive intraoperative culture result.

Operative Resection of a Chronic Flail Chest Nonunion Revealing Septic Pseudarthrosis: A Case Report

We report a case of chest wall resection for painful chest wall nonunion, 5 years after traumatic flail chest and a first attempt at surgical treatment. The decision was made to perform surgery again after 2 years of unsuccessful well-conducted analgesic treatment. During surgery, we found the same sites of pseudarthrosis and decided to perform parietectomy of the fifth, sixth, and seventh ribs. A Gore-Tex patch was used to bridge the gap created by the resection. In immediate postoperative care, the patient's pain was quickly and sufficiently eased by stage 1 and 2 pain killers. The results of bone samples taken from the pseudarthrosis sites all found Propionibacterium acnes. Five months after surgery, the patient had considerable improvement in pain sensations. Computed tomography showed healing of ribs, the plate in place, and no sign of complications.

Clavicle Nonunion and Malunion: Surgical Interventions for Functional Improvement

Clavicle nonunion and malunion are relatively uncommon but, when symptomatic, can result in pain and dysfunction that requires surgical intervention. Various reconstructive and grafting techniques are available to achieve stable fixation and union. In the setting of persistent nonunion, vascularized bone grafting may be necessary. A thorough understanding of the patient's type of nonunion and potential for healing is crucial for achieving satisfactory results because is thoughtful preoperative planning and surgical fixation.

Intercalary Tricortical Iliac Crest Graft for Treatment of Midclavicle Nonunion With Bone Loss: Two Case Reports and Review of Literature

Several articles support the use of cancellous iliac crest bone grafting in the treatment of clavicle nonunion; however, there is very little literature on the use of tricortical iliac crest grafts in the setting of clavicle nonunion with bone loss. When it has been studied, tricortical grafting has been shown to produce radiologically confirmed union in the clavicle, leaving patients satisfied with the ultimate outcome. We present two cases of clavicle fracture nonunion successfully treated with tricortical interposition bone grafting. In the first case, a 45-year-old female presented with an atrophic left midshaft clavicle fracture nonunion with failed hardware that had undergone two previous attempts at fixation without achieving union. She was treated with a structural interposition iliac crest bone graft with plate fixation and regained full painless function of the arm with radiographic fracture union. In the second case, a 50-year-old male presented after a left midshaft clavicle fracture that had undergone acute stabilization, followed by revision for nonunion that was unsuccessful, resulting in persistent nonunion with bone loss. He was treated with a tricortical iliac crest bone graft and plate fixation. Cultures from the time of surgery did grow Staphylococcus epidermidis and Propionibacterium acnes, and he was treated with intravenous vancomycin for six weeks. The patient's clavicle went on to union and he regained full, painless function by his six-month follow-up visit. These cases demonstrate the use of tricortical interposition bone grafting with compression plating as a viable option for rare instances in which previous surgical intervention has failed to progress a midshaft clavicle fracture to union.

Revision surgery after failed surgical treatment of midshaft clavicle fractures is often associated with positive detection of bacteria

BACKGROUND

Midshaft clavicle fractures are common, and the proportion of patients treated surgically has increased in recent years. With this increase in surgical treatments, the complication rate, for instance of infection, non-union, or implant failure, has also risen. This study evaluates the frequency of pathogen detection during revision surgeries occurring after a prior failed osteosynthesis of midshaft clavicle fractures.

METHODS

All patients treated in our hospital with a prior failed surgical therapy of a clavicle midshaft fracture between January 2013 and March 2022 were screened. Epidemiological data, intraoperative tissue samples, sonication, and the type of revision surgery were assessed. A postoperative follow-up at a minimum of 6 month was defined and osseous consolidation was verified.

RESULTS

Twenty-one patients (twelve male and eight female) were included with a mean age of 40.4 ± 14.1 years. Eleven of the patients showed pathogen detection (Group I), and seven remained without (Group II). A significant difference in age existed between Groups I and II (36.1 ± 12.8 and 51.6 ± 11.5, p  ≤ 0.05). The three most common pathogens were Cutibacterium acnes (n = 7), Staphylococcus epidermidis (n = 4), and Staphylococcus sacchorlyticus (n = 3), respectively. Thirteen patients presented for a follow-up. In nine patients (69%), bone healing was detectable. Four patients received a second revision surgery.

CONCLUSION

Revision surgery frequently shows pathogen detection without signs of infection. Cutibacterium acnes is the most common pathogen. Despite pathogen detection, bone healing can be achieved with revision surgery, although the rate of repeat revision surgeries is high.

[Atrophic sternum nonunion-Case report based on the nonunion scoring system]

Pseudarthrosen nach Sternotomien sind rar und meist gut im Rahmen operativer Revisionen zu behandeln. Bei fehlgeschlagenen Revisionen ist ein differenziertes Vorgehen notwendig, das sowohl die biologischen wie auch biomechanischen Rahmenbedingungen berücksichtigt. Es wird über den Fall einer therapierefraktären atrophen Pseudarthrose nach auswärtig erfolgloser Revision berichtet. Diese wurde durch ein Therapievorgehen, orientiert an den Kriterien des Non Union Scoring System (NUSS), erfolgreich behandelt. Die Versorgungsstrategie wie auch der erfolgreiche Behandlungsverlauf werden dargestellt.

Utilization of Tranexamic Acid in Surgical Orthopaedic Practice: Indications and Current Considerations

Tranexamic acid (TXA) is a lysine analog that exhibits an anti-fibrinolytic effect by directly preventing the activation of plasminogen as well as inhibiting activated plasmin from degrading fibrin clots, thereby promoting hemostasis and reducing the duration and quantity of blood loss. The aims of this study were to summarize the indications, routes of administration, safety, and clinical outcomes of TXA use throughout the different subspecialities in orthopedic surgery. Given that orthopedic procedures such as TKA, THA, fracture fixation, and various spine surgeries involve significant intraoperative blood loss, TXA is indicated in providing effective perioperative hemostasis. Additionally, use of TXA in orthopedic trauma has been indicated as a measure to reduce blood loss especially in a group with potential for hemodynamic compromise. TXA has been implicated in reducing the risk of blood transfusions in orthopedic trauma, joint surgery, and spine surgery, although this effect is not seen as prominently in sports medicine procedures. There remains disagreement in literature as to whether TXA via any route of administration can improve other clinically significant outcomes such as hospital length of stay and total operative time. Procedures that rely extensively on clarity on visualization of the surgical field such as knee and shoulder arthroscopies can greatly benefit from the use of TXA, thereby leading to less intraoperative bleeding, with better visual clarity of the surgical field. While most studies agree thrombosis due to TXA is unlikely, new research in cells and animal models are evaluating whether TXA can negatively impact other aspects of musculoskeletal physiology, however with conflicting results thus far. As of now, TXA remains a safe and effective means of promoting hemostasis and reducing intraoperative blood loss in orthopedic surgery.

Diagnosis of orthopaedic-implant-associated infections caused by slow-growing Gram-positive anaerobic bacteria - a clinical perspective

Slow-growing Gram-positive anaerobic bacteria (SGAB) such as Cutibacterium acnes are increasingly recognized as causative agents of implant-associated infections (IAIs) in orthopaedic surgeries. SGAB IAIs are difficult to diagnose because of their non-specific clinical and laboratory findings as well as the fastidious growth conditions required by these bacteria. A high degree of clinical suspicion and awareness of the various available diagnostic methods is therefore important. This review gives an overview of the current knowledge regarding SGAB IAI, providing details about clinical features and available diagnostic methodologies. In recent years, new methods for the diagnosis of IAI were developed, but there is limited knowledge about their usefulness in SGAB IAI. Further studies are required to determine the ideal diagnostic methodology to identify these infections so that they are not overlooked and mistakenly classified as aseptic failure.

Cutibacterium acnes in shoulder surgery: a scoping review of strategies for prevention, diagnosis, and treatment

BACKGROUND

Cutibacterium acnes is a commensal, gram-positive, facultatively anaerobic bacillus that resides in the dermis. Historically thought to be a contaminant when identified on cultured specimens, recent advances in diagnostic technology have now implicated it as the most common organism responsible for postoperative shoulder infections. Despite a recognition of the role of this organism and a significant research interest in recent years, there is clear lack of consensus guideline on strategies to prevent, diagnose, and treat postoperative shoulder infection.

METHOD

The electronic databases PubMed, MEDLINE, CINAHL, Scopus, and Web of Science were searched in March 2020. All experimental and nonexperimental studies that investigate C acnes in shoulder surgery were included. Inclusion was limited to articles published after 2000 and written in English; reviews, gray literature, or abstracts were excluded. A total of 70 studies were included in this review. This scoping review was performed in accordance with the Extended Preferred Reporting Items of Systematic Reviews and Meta-Analyses Statement for Scoping Reviews (PRISMA-ScR).

RESULTS

Standard surgical prophylactic regimens such as intravenous antibiotics and topical chlorhexidine are ineffective at removing C acnes from the deep layer of the dermis, and there is a shift toward using topical benzoyl peroxide with significantly improved efficacy. An improved understanding of the bacteria has demonstrated that a prolonged culture time of up to 14 days is needed, especially in cases of established infection. Advances in diagnostics such as sonication and molecular-based testing are promising. Although usually thought to be susceptible to a broad range of antibiotics, resistance is emerging to clindamycin. An improved understanding of its ability to form a biofilm highlights the difficulty in treating an established infection.

CONCLUSION

The role of C acnes causing postoperative infection following shoulder surgery is being increasingly recognized. Strategies for prevention, diagnosis, and treatment have been outlined from both an antimicrobial and surgical perspective. A number of these strategies are emerging and require further research to demonstrate efficacy before implementation into clinical guidelines.

Medial Femoral Condyle Vascularized Bone Graft for Treatment of Midshaft Clavicle Recalcitrant Nonunion With Use of the Transverse Cervical Artery as an Anastomosis

Vascularized medial femoral condyle bone grafts have been reported to be a reliable treatment for recalcitrant bony nonunions of the extremities. Although clavicle fracture nonunions are rare after treatment with open reduction internal fixation, symptomatic nonunions can be a challenge. The medial femoral condyle vascularized bone graft has been described as a treatment option for clavicle nonunions with the thoracoacromial trunk as the recipient anastomosis site. This case illustrates how the transverse cervical artery and accompanying veins can be used as an anastomosis when the thoracoacromial trunk is inaccessible because of previous surgical- and infection-related scaring. At the final follow-up, the patient had returned to full duty and resumed competitive triathlons. Radiographs demonstrated complete healing of clavicle fracture.

Axillary Artery Pseudoaneurysm After Revision Plate Osteosynthesis of a Midshaft Clavicle Fracture Nonunion: A Case Report

CASE

A patient with history of nonunion repair of traumatic midshaft clavicle fracture was referred to our orthopaedic trauma clinic for new-onset shoulder pain and paresthesias involving the ipsilateral arm. Computed tomography angiography revealed an axillary artery pseudoaneurysm adjacent to the instrumentation and recurrent nonunion of the fracture site. The patient underwent coil embolization of the pseudoaneurysm and nonunion repair.

CONCLUSION

This case demonstrates that iatrogenic neurovascular injury during clavicle fracture nonunion repairs can present in a delayed fashion requiring more thorough clinical and imaging evaluation to achieve successful treatment.

Bone Flap Resorption Associated with Indolent Propionibacterium acnes Infection After Cranioplasty: Case Report with Pathological Analysis

BACKGROUND

Autologous bone resorption is a frequent complication of cranioplasty, often necessitating reoperation. The etiology of this phenomenon is unknown, although it has recently been associated with indolent Propionibacterium acnes infection.

CASE DESCRIPTION

A 59-year-old man initially presented with a traumatic acute subdural hematoma treated with emergent decompressive hemicraniectomy and hematoma evacuation. His bone flap was cryopreserved. He underwent cranioplasty with autologous bone 3 months later. Over the subsequent 14 months, serial imaging demonstrated progressive bone flap resorption, ultimately requiring repeat cranioplasty with a custom allograft. Although there was no evidence of infection at the time of repeat cranioplasty, routine culture swabs were taken and grew P. acnes after the patient had been discharged home. Pathologic analysis of the fragments of the original bone flap that were removed demonstrated osteonecrosis with marrow fibrosis but no evidence of inflammation or infection. He was treated with 6 weeks of intravenous antibiotics and had no evidence of infection at 8-month follow-up.

CONCLUSIONS

Indolent P. acnes infection can precipitate autologous bone flap resorption. While the mechanism of this is unknown, pathologic analysis of a partially resorbed bone flap in the setting of an indolent P. acnes infection found no evidence of an infectious process or inflammation within the bone. Further studies are needed to elucidate the mechanism of action of P. acnes in bone flap resorption.

The challenge of nonunion after osteosynthesis of the clavicle: is it a biomechanical or infection problem?

Introduction

The nonunion rate has been reported between 0.1% and 15%. There are also several predisposing factors for the onset of complications: general factors connected with the patient and specific factors related to the fracture site. The purpose of our study is to review the etiology of nonunion of the clavicle in its atrophic form and investigate the outcomes of the revision treatment in a single step.

Materials and methods

Retrospective study on 71 patients suffering from nonunions due to the following treatments: conservative in 13 patients; plate fixation in 12; closed reduction and fixation with K-wire in 24; open reduction and fixation with K-wire. All patients were operated on in beach chair position and classic approach to the clavicle by incising the previous surgical scar. The clinical and radiographic criteria for evaluating the outcomes were: the Short Form (12) Health Survey (SF-12), the Constant Shoulder Score (CSS) and the Disability Disabilities of the Arm, Shoulder and Score (DASH) and radiographic Union Score (RUS) for bone healing. The evaluation endpoint was set at 12 months.

Results

Blood and culture tests showed 22 infected nonunions and 49 atrophic or oligoatrophic. In only 10 cases, before surgery, the inflammatory markers were positive. The isolated microorganisms were resistant to common antibiotics. In 70 out of 71 cases, plates and screws on the upper side and fibula allogenic splints at the bottom, associated with cancellous bone grafts taken from the patients' iliac crests, were implanted. In one case, however, it was decided to implant the plate on the front edge of the clavicle and the fibula allogeneic splint on the posterior margin, also associated with a cancellous bone graft taken from the patient's iliac crest. The radiographic bone healing was observed in 107.8 (range 82-160) days for the aseptic nonunions, while in 118.4 (range 82-203) days for the septic ones. The non-healing case was a serious failure that led to asubtotal excision of the clavicle.

Conclusions

The importance of classification and study of nonunions are essential to achieve positive outcomes. The guiding principle of our work is that aseptic nonunions heal in the operating room, while infected nonunions can be challenged and defeated on the operating table. Restoring the correct length of the clavicle interconnection between the sternum and the shoulder cingulum is indispensable to avoid functional deficits of the upper limb. The fibula splint and the tricorticale bone graft have both mechanical and strong biological values to quickly heal the nonunion. The return to pre-injury quality of life has to be our main goal.

Propionibacterium acnes biofilm is present in intervertebral discs of patients undergoing microdiscectomy

Background

In previous studies, Propionibacterium acnes was cultured from intervertebral disc tissue of ~25% of patients undergoing microdiscectomy, suggesting a possible link between chronic bacterial infection and disc degeneration. However, given the prominence of P. acnes as a skin commensal, such analyses often struggled to exclude the alternate possibility that these organisms represent perioperative microbiologic contamination. This investigation seeks to validate P. acnes prevalence in resected disc cultures, while providing microscopic evidence of P. acnes biofilm in the intervertebral discs.

Methods

Specimens from 368 patients undergoing microdiscectomy for disc herniation were divided into several fragments, one being homogenized, subjected to quantitative anaerobic culture, and assessed for bacterial growth, and a second fragment frozen for additional analyses. Colonies were identified by MALDI-TOF mass spectrometry and P. acnes phylotyping was conducted by multiplex PCR. For a sub-set of specimens, bacteria localization within the disc was assessed by microscopy using confocal laser scanning and FISH.

Results

Bacteria were cultured from 162 discs (44%), including 119 cases (32.3%) with P. acnes. In 89 cases, P. acnes was cultured exclusively; in 30 cases, it was isolated in combination with other bacteria (primarily coagulase-negative Staphylococcus spp.) Among positive specimens, the median P. acnes bacterial burden was 350 CFU/g (12 - ~20,000 CFU/g). Thirty-eight P. acnes isolates were subjected to molecular sub-typing, identifying 4 of 6 defined phylogroups: IA₁, IB, IC, and II. Eight culture-positive specimens were evaluated by fluorescence microscopy and revealed P. acnes in situ. Notably, these bacteria demonstrated a biofilm distribution within the disc matrix. P. acnes bacteria were more prevalent in males than females (39% vs. 23%, p = 0.0013).

Conclusions

This study confirms that P. acnes is prevalent in herniated disc tissue. Moreover, it provides the first visual evidence of P. acnes biofilms within such specimens, consistent with infection rather than microbiologic contamination.